Pneumatic starting device



Aug. '28, 1951 y R. HUBER 2,555,849

PNEUMATIC STARTING DEVICE Filed Mafoh 18, 1947 1g Z A INVENTOR W W H15 ATTURNE Y5 Pa ten teci Aug. 28,

PNEUMATIC STARTING DEVICE Robert Huber, Paris, France, assignor to Societe dEtudes et de Participations, Eau, Gaz, Electricite, Energie, S. A., Geneva, Switzerland, a society of Switzerland Application March 18, I947, Serial No. 735,520 In France March 22, 1946 6 Claims. (01. (iii-14) The present invention relates to pneumatic starting devices for machines and more especially, although not exclusively, free piston machines (motor compressors or auto-generators).

Its object is to provide a device of this kind. which is better adapted to meet the requirements of practice than those used for the same purpose up to the present time.

Preferred embodiments of my invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example, and in which:

Fig. l is a diagrammatic axial sectional view of a free piston auto-generator provided with a starting device according to the invention;

Fig. 2 is a similar view of a machine of the same kind provided with a. starting device made according to another embodiment of the invention.

The auto-generators to which the invention is applied in the examples hereinafter described are of a conventional type. For instance, that shown by Fig. 1 includes a motor cylinder I provided with a fuel injector 2 and air inlet orifices 4 (for scavenging and fuel mixture supply) and exhaust orifices 5 (for the mixture formed by the combustion gases and the excess of said air, this mixture constituting the gas to be supplied by the auto-generator).

In this cylinder l works a motor piston 3, which controls the inlet ports 4 and exhaust ports 5, and this motor piston is rigid with a compressor piston 6, which cooperates with a compressor cylinder 1 so as to divide the latter into two chambers. One of these chambers (that nearer to the motor cylinder, which will be hereinafter called inner chamber) is provided with an inlet valve 8 and an outlet valve 9 and constitutes the compressor space proper, in which is compressed the air intended for scavenging cylinder l and mixing with fuel therein. This air flows past valve 9 into a reservoir 10 which surrounds cylinder 1. The other of the two above mentioned chambers, or outer chamber, constitutes, during normal operation of the auto-generator, a'pneumatic energy accumulator capable'of storing up energy during the outward stroke of pistons 3 and 6 and of delivering this energy to said pistons for their inward stroke.

In order to start this auto-generator, I introduce into one of the above mentioned chambers, for instance the pneumatic energy accumulator constituted by the outer chamber of compressor cylinder 1, a certain amount of air previously stored up in a reservoir ll, filled from a source I2 of air under pressure, a conduit IS with a valve or cook 14 being interposed between source 12 and reservoir II.

I provide, to bring the inside of reservoir ll into communicationwith the inside of the starting chamber of the auto-generator, an orifice I5 controlled by a valve [6 rigid with a piston ll movable in a cylinder 18 provided inside reservoir ii, a spring l9 tending to keep valve it closed.

Concerning the two chambers formed inside cylinder :8 on either side of piston ii, in the embodiment of my invention illustrated by Fig. 1, one of these chambers (the lower one) is connected with a conduit 20 in communication with the compressed air inlet and the other of these chambers (the upper one) is connected with the inside of reservoir ll through an orifice 2|. In the other embodiment of my invention, illustrated by Fig. 2, both of these chambers are in communication with the inside of reservoir H, respectively through calibrated orifice 22 and orifice 21'. Thus, while reservoir II is being filled and prior to the working of the starting device, the air pressures on opposite sides of piston l1 balance each other and valve 16 is strongly applied against its seat'by spring I9. I may further provide acheck valve in the air inlet conduit to reservoir ll. Thus, in the embodiment of Fig. 1, such a valve 23' is provided in the passage leading from conduit 20 to reservoir II. In the embodiment of Fig. 2, check valve 24 is' provided at the outlet of'conduit l3 into reservoir l I.

With a starting device such as above described, operation of the starting device is obtained by suddenly reducing the pressure acting upon the side of piston" i-I' opposed to valve l6. This causes valve It to be moved away from its seat and the air under pressure present in reservoir ll suddenly enters the starting chamber to push pistons 3i toward their inner dead center positions, near which fuel is injected and ignited.

In order to obtain correct starting operation, the air under pressure present in the chamber of cylinder I-Bopposed to valve [6 must be evacuated' very quickly. Otherwise, valve It might drop back onto its seat [5 before the whole of the compressed air stored up in reservoir H has entered the starting chamber of cylinder 7.

Up to the present time, in starting devices of this kind, the exhaust of air under pressure from the above mentioned chamber of cylinder [8 took place through the conduit l3 used for filling reservoir I Ffrom source [2, cock l'd' being so devised that, in one of its positions, it places this chainher of cylinder I8 in communication with the atmosphere. In order to obtain a quick outflow of air under pressure from said chamber, conduit I3 is to be given a large section, especially when cock I4, which is located at the plant control station, is at a relatively great distance from reservoir H. However, for practical purposes, it is often dificult to find the room necessary for conduits-l3 of large diameter. The question of the available space becomes still more difiicult to solve when the plant includes several autogenerators the starting of which is to be controlled from a central station.

In order to obviate these difficulties, according to a feature of my invention, I provide an exhaust conduit 25 distinct from inlet conduit I3.

, This discharge conduit 25 which can, without any difficulty, be made very short and of relatively large section, directly connects with the atmosphere the chamber of cylinder I8 that is directly opposed to valve 16. Furthermore, I provide this discharge conduit 25 with a control valve 26.

When valve 26 is opened, said chamber of cylinder I8, is immediately and completely discharged into the atmosphere so that any danger of accidental closing of valve I6 before the desired time iswholly eliminated.

The opening of valve 26 may be performed either under the effect of manual means or automatically, for instance in response to a given variation of the pressure in reservoir II.

Fig. 1 shows an embodiment of an arrangement for manual operation of the device. With this arrangement, valve 26 is operated by a servomotor means constituted by a piston 21 movable inside a cylinder 28, this piston being adapted to act upon the stem 29 of valve 26 under the action of the air under pressure present in the chamber of cylinder 28 opposed to stem 29. This last mentioned chamber communicates with the inside of reservoir II through a calibrated oriiice 30. Furthermore, manually operated cock I4 is arranged in such manner that after it has been rotated through an angle of 90 from the position shown by Fig. 1, this cock, while cutting off the communication between conduit I3 and the source I2 of air under, pressure, places conduit I3 in communication with the atmosphere. Finally, I provide, at the inlet of conduit (belonging to the means for supplying air under pressure to reservoir II) a check valve 3I.

, The device illustrated by Fig. 1 works in the following manner. Reservoir II and both of the chambers of cylinder I8 have first been filled with .is placed in the position connecting conduit I3 with the atmosphere. This causes a sudden drop of the pressure which, up to then, had kept servomotor piston 2'! ata distance from the stem 29 of valve 26, and the pressure acting upon the opposed face of this piston 21 pushes it against stem 29, thus causing valve 26 to open and to bring the chamber of cylinder I8 located under piston I1 into communication with the atmosphere. through large conduit 25. Consequently, piston I I and valve I6 move downwardly under the effect of the pressure in the upper chamber of cylinder I8, thus placing the starting chamber of cylinder 1 in communication with reservoir II.

In the embodiment of Fig. 2, the opening of valve 26 is automatically ensured as soonas the vpressure in reservoir II reaches a predetermined value. For this purpose servo-motor piston 21,

which controls valve 26 in the same manner as in the embodiment of Fig. 1, is connected through a link 32 with a lever 33 pivoted at 34 to a fixed arm 35, the other end of said lever 33 being nor= mally locked by a knuckle device (links 361,362) in a position for which piston 21 is held at a distance from the stem 29 of valve 26. The joint 31 of the links in question is normally applied by a spring 38 against an abutment 39 rigid with a piston 40 one of the faces of which is subjected to the action of a spring 4|, whereas the other face is subjected to the action of the pressure existing in reservoir II, transmitted through a conduit 42 extending between said reservoir II and the outer chamber of the cylinder 43 of said piston 40.

Furthermore, check valve 24, provided between inlet conduit I3 and reservoir I I is arranged to coact with link 32 or lever 33 in such manner as to be kept in the open position as long as piston 21 is kept away from valve stem 29.

This device works as follows:

Reservoir II is filled with air under pressure. At the beginning, abutment 31 (urged by spring 4| which acts upon piston 40), knuckle device 361-362, lever 33 and piston 21 are in the position shown by Fig. 2. In this position, servomotor piston 21 is prevented from moving toward valve stem 29, despite the fact that the face. of this piston opposed to said valve stem is subjected to the action of the pressure existing in reservoir II, whereas its-otherface is subjected to the atmospheric pressure supplied through conduit 44, which opens into conduit 25.

As soon as the pressure in reservoir II reaches a predetermined value, it causes piston 40 to move toward the left, thus bringing the knuckle system into its other position, shown in dotted lines. Lever 33 and servomotor piston 21 are no longer locked in the position of Fig. 2 and the pressure in reservoir II pushes piston 21 against the stem 29 of valve 26, whereby said valve opens and the air under pressure imprisoned in the lower cham ber of cylinder I8 suddenly escapes to the atmosphere through conduit 25. Valve I6 opens and the auto-generator is started.

At the latest when the machine is stopped, when the air cushion is emptied, the spring 45 which acts upon piston 21 and the springs 38 and M which act respectively upon system 361-362 and piston 49, bring back these parts into their initial positions shown by Fig. 2, and the starting device is ready for further operation.

According to another feature of my invention, means are provided for adjusting in accordance with the thermic state of the machine "to be started, the pressure under which the starting air is supplied to the-starting space of this machine. For this purpose, I provideon the machine, at a place where the temperature varies in accordance with the general thermic state of the machine, for instance in casing ID, a thermostat 46 adapted to act upon means for: adjusting the pressure of the starting air in reservoir I I. The means in question may for instance include a valve for limiting the pressure in reservoir I I by allowing air to escape from said reservoir into the atmosphere as soon as the pressure in said reservoir exceeds a predetermined value.

Such a valve is shown at 41 in Fig. 1. Valve 41 is normally kept by a spring 48 in the position that closes orifice 49 provided in the wall of reservoir I I. Valve 41 is further subjected to the nected with the thermostat through a conduit 5|, whereby the pressure inside said box 50 is adjusted by thermostat 48 as a function of the temperature acting on said thermostat, said box 50 being mounted in such manner that its action is opposed to that of spring 48. The higher the temperature in casing Hi and therefore the pressure in deformable box 59, the smaller the force tending to keep valve 4'! closed. Therefore, the maximum pressure of the starting air in reservoir II is the lower as the general thermic state of the machine to be started is higher.

In the embodiment of Fig. 2, the thermostatic deformable box 50 acts upon abutment 39, this deformable box acting in the same direction as the pressure in reservoir H transmitted through conduit 42. The action is the same as in the preceding embodiment since the deformable box influences the value of the pressure in reservoir II for which lever 33 will cease to be locked in the position preventing the opening of valve 26.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and efficient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

1. A pneumatic starting device for a free piston machine which comprises, in combination, a source of gaseous fluid under pressure, a reservoir to contain this fluid for starting said machine, valve means between said reservoir and said machine, means forming a variable volume chamber for operating said valve means, said valve operating means being responsive to variations of the fluid pressure in said chamber normally to keep said valve means closed as long as said fluid pressure is above a given value and to open said valve means in response to a drop of the pressure in said chamber below said value, means for placing said source in communication with both said reservoir and said chamber, servomotor means operative by the fluid pressure in said reservoir for discharging fluid from said chamber through a path wholly distinct from the means for placing the source in communication with the reservoir and the chamber, and means for cutting off said communication at least substantially simultaneously with the discharging of said fluid from said chamber.

2. A pneumatic starting device for a free pis= ton machine which comprises, in combination, a source of gaseous fluid under pressure, a reservoir to contain said fluid for starting said machine, valve means between said reservoir and said ma= chine, means forming a variable volume chamber for operating said valve means, said valve operating means being responsive to variations of the fluid pressure in said chamber normally to keep said valve means closed as long as said fluid pressure is above a given value and to open said valve means in response to a drop of the pressure in said chamber below said value, means for placing said source in communication with both said reservoir and said chamber, an outlet conduit between said chamber and the atmosphere, a valve to control said conduit, servomotor means operative by the fluid pressure in said reservoir for opening said valve and means for cutting oii the communication between said source and said reservoir and said chamber at least substantially simultaneously with the opening of said last mentioned valve.

3. A pneumatic starting device for a free piston machine, which comprises, in combination, a source of gaseous fluid under pressure, a reservoir to contain said fluid for starting said machine, valve means between said reservoir and said machine, means forming a variable volume chamber for operating said valve means, said valve operating means being responsive to variations of the fluid pressure in said chamber nor= mally to keep said valve means closed as long as said fluid pressure is above a given value and to open said valve means in response to a drop of the pressure in said chamber below said value, means for placing said source in communication with both said reservoir and said chamber, an outlet conduit between said chamber and the atmosphere, a valve to control said conduit, manually controlled servomotor means operative by the fluid pressure in said reservoir for opening said valve and means for cutting off the com= munication between said source and said reservoir and said chamber at least substantially simultaneously with the opening of said last mentioned valve.

4. A pneumatic starting device for a free piston machine which comprises, in combination, a source of gaseous fluid under pressure, a reservoir to contain said fluid for starting said machine, valve means between said reservoir and said machine, means forming a variable volume chamber for operating said valve means, said valve operating means being responsive to variations of the fluid pressure in said chamber normally to keep said valve means closed as long as said fluid pressure is above a given value and to open said valve means in response to a drop of the pressure in said chamber below said value, means for placing said source in communication with both said reservoir and said chamber, an outlet conduit between said chamber and the atmosphere, a valve to control said conduit, a cylinder in said reservoir, a piston in said cylinder, a conduit opening into one end of said cylinder, passages connecting said end of said cylinder with said reservoir and said chamber, check valves in said passages to permit the flow of fluid only from said cylinder end toward said reservoir and said chamber, the other end of said cylinder being in permanent communication with said reservoir, means operative by displacement of said piston toward the first mentioned end of said cylinder for opening said last mentioned valve and man ual valve means for connecting said conduit alternately with said source of fluid and with the atmosphere.

5. A pneumatic starting device for a free pis ton machine which comprises, in ccmbination, a source of gaseous fluid under pressure, a reser voir to contain this fluid for starting said-ma chine, valve means between said reservoir and said machine, means forming a variable volume cham= her for operating said valve means, said valve operating means being responsive to variations of the fluid pressure in said chamber normally to keep said valve means closed as long as said fluid pressure is above a given value and to open said valve means in response to a drop of the pressure in said chamber below said value, means for placing said source in communication with both said reservoir and said chamber, an outlet conduit between said chamber and the atmosphere, a valve to control said conduit, automatic servomotor means operative by the fluid pressure in'said reservoir for opening said valve in response to a rise of the pressure in said reservoir to' a predetermined value and means for cutting ofi the communication between said source and said reservoir and said chamber simultaneously with the opening of said last mentioned valve.

7 6. A starting device according to claim 2 further including a discharge valve for limiting the maximum pressure inside said reservoir, spring means for elastically opposing the opening of said valve, and thermostatic means responsive to variations in the temperature of said free piston machine for automatically adjusting said spring means.

ROBERT HUBER.

8 1 REFERENCE$ CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 7 Name Date 1,646,640 Daniel Oct. 25, 1927 2,168,828 Pateras Pescard Aug. 8, 1939 2,377,227 Griswold May 29, 1945 FOREIGN PATENTS Number Country Date Great Britain June 23, 1906 

